Afrida, E., Syahril, M. and Koko Tampubolon 2022. Optimization of soybean yield in ultisols through adaptive varieties screening and plant growth promoting Rhizobacter. Bioscience Journal. 38, (Feb. 2022), e38013. DOI:https://doi.org/10.14393/BJ-v38n0a2022-57214.